Irish transparency activists have raised concerns around foreign interference from US pro-life groups ahead of the upcoming abortion referendum on Friday.

US anti-abortion activists, describing themselves as ‘journalists,’ have been campaigning across the historically Catholic country, calling on Irish citizens to vote ‘no’ to repealing the 8th amendment. If the referendum passes, it would pave the way for liberalizing the country’s strict abortion laws.

Online ads purchased outside Ireland have also been targeting the Irish electorate, sparking concerns from politicians and campaigners about illegal foreign influence. Under Irish law, foreign citizens and groups are not allowed to make any financial donations to Irish campaign groups.The ad bans do not extend online or on social media, meaning anyone is open to buying an ad on platforms like Facebook or Google.

Earlier this month, however, Facebook responded to worries about such ad buys by banning all foreign-bought ads related to the vote. Google followed suit with the announcement that it would suspend all ads relating to the referendum, including advertisements on YouTube and Google Adwords.

Despite these measures, some ads relating to Ireland’s abortion referendum appear to have slipped through the cracks, according to the Transparency Referendum Initiative - a group set up ahead of the referendum to monitor paid political ads on social media.

TRI Co-founder Liz Carolan shared screenshots of such ads still appearing on news sites including The Guardian, The Atlantic, and ProPublica.

We'll also continue to try understand the other online ads. Google say they banned #8thref ads, but we are still having large numbers of ads on websites & apps reported to us, perhaps by other co. like Adobe. Share ads you see with #TREF or via DM. Here's a sample from weekend pic.twitter.com/oyWtRJc7KJ

Or perhaps @TheAtlantic can explain why Irish people are getting political ads through its site and app - these were seen on Monday - do you use GoogleAds? If so could you check how these ads got through the ban? If not, who is providing this service? Cc @andersen@davidfrumpic.twitter.com/v9Fh7lEzOQ

Among the groups targeting Irish voters are Colorado-based anti abortion group Let Them Live and New York-based pro-life group Expectant Mother Care-EMC FrontLine Pregnancy Centers.

Campaigners from Let Them Live, founded by Emily Faulkner, travelled to Ireland earlier this month as self-styled pro-life ‘journalists.’ According to posts on their Facebook page, they have campaigned on the streets of Dublin and put up posters across the country.

Faulkner confirmed to RT via email that the group had travelled to Ireland to campaign in the referendum, saying they “felt called to be here to defend the unborn and be a voice for the voiceless.”

TRI has also identified at least seven groups purporting to provide neutral information on the referendum, but which are actually offering biased information towards one side or another.

Earlier this month, Irish journalist and transparency campaigner Gavin Sheridan pointed to one of these groups, Undecided8, highlighting that the website was hosted in New Jersey and there were no details provided on the people behind it.